Tubing for lining pipes and method for producing the same

ABSTRACT

The invention relates to a tubing arrangement for lining pipes, to a method for producing the same and to a method for lining pipes. The invention especially relates to superpressure pipes with an internal working pressure of greater than 16 bar. In order to prevent the pipe tubing from being damaged in the case of accidents or when the pipes are placed out of service, the tubing ( 1 ) has a barrier layer ( 1   b ) which has a gas permeation of less than 1 ml/(bar d m 2 ) for nonpolar gases and of less than 0.1 ml/(bar d m 2 ) for polar gases. Preferably, the gas permeation ranges from 0.0001 ml/(bar d m 2 ) to 0.01 ml/(bar d m 2 ).

BACKGROUND OF THE INVENTION

The present invention relates to an arrangement comprising a pipe andtubing lining same, and a method of producing this arrangement. The mainfield of application is in pipelines in which a fluid, e.g. natural gas,is transported under high pressure.

There is a known method of introducing externally coated tubing forlining a pipe with an aperture at the beginning of the pipe by inversioninto this pipe, the external surface of the tubing being inverted andglued to the inner wall of the pipe to be lined. The tubing can howeveralso be introduced into a pipe by being pulled in (without beinginverted) and then glued.

The types of tubing previously used for this purpose consist mainly of athe coating. Thus pores, which are located in the adhesive itself orwithin the textile structure which is not completely saturated withadhesive, have the same pressure applied to them as prevails in thelined pipe.

As long as the operating pressure is maintained, as a result of thebalance of pressures no damage is to be expected, but some will probablyoccur with a sudden drop in pressure, e.g. where there is an accident tothe pipe or some other operational failures, but even also at times whenthe pipe is taken out of service as planned. In this case, the completeoperating pressure continues to be found in the pores describedpreviously, since this pressure cannot suddenly escape via the coatingtowards the centre of the pipe, i.e. the flow area of the fluid to betransported with the pipe. Whilst in the region between the inner pipewall and the coating, the operating pressure of the superpressure pipecontinues to be maintained, in the flow area there is e.g. onlyatmospheric pressure. As a result of this just low counter pressure,there are then expansion processes of the gases trapped in the pores,which are connected with bursting of the tubing (formation of bulges) oreven complete tearing of the tubing sheath from the pipe wall.

From BE 886 312 A is already known tubing for transporting hot liquids,especially hot water. In order to prevent damage to the tubing material,in particular an increase in permeability by the hot liquids duringoperation, the interior of the tubing is lined with an aluminium layerwhich is impermeable to the liquids.

The object underlying the present invention is to make available anarrangement comprising a pipe and tubing lining same and a correspondingmanufacturing method, in which when there is a drop in pressure in theflow area, damage to the lining and the safety and cost risks connectedtherewith do not arise.

This object is accomplished in relation to the arrangement by patentclaim 1 and in relation to the manufacturing method by patent claim 19.

Because there is associated with the tubing blank a barrier layer whichhas a permeation of less than 1 ml/(bar d m²) for nonpolar gaseoussubstances and a permeation of less than 0.1 ml/(bar d m²) for polargaseous substances (d=day), the penetration of the tubing by gases isprevented from the beginning or the diffusion of gases into the spacebetween the pipe inner wall and the flow area is slowed down in such away that even after many years in continuous service, e.g. 50 years, asudden drop in pressure in the interior of the tubing would not causeany damage to the lining.

Advantageous developments of the present invention are given in thedependent patent claims.

A barrier layer is preferred in which the permeation of nonpolar andpolar gaseous substances is in the range between 0.0001 ml/(bar d m²)and 0.01 ml/(bar d m²).

A particularly advantageous embodiment of the tubing provides for it tobe realised as a tubing composite, i.e. multilayer, one layer beingconfigured as the barrier layer. This makes it possible for conventionalwoven hoses, which have been otherwise coated according to prior art inan extruder with thermoplastic plastics materials and have an inadequatediffusion resistance, also to continue to be used for the tubing. Thepartitioning effect of the tubing is caused in this embodiment merely bythe barrier layer.

The barrier layer consists advantageously of metal, especiallyaluminium, titanium, copper, iron, zinc, nickel, lead, chromium oriron-zinc and lead-tin alloys. The barrier layer preferably has athickness of between 10 and 100 μm.

Other suitable materials for the barrier layer are organic substancessuch as polyvinyl alcohols (PVA) and copolymers of same, liquid crystalpolymers (LCP), polyamides (PA), polyacrylonitrile,polyvinylidene-chloride (PVDC), epoxy resins (EP) or organosiliconcompounds and inorganic substances such as silicon oxide (SiO_(x) withx=2) or aluminium oxide (Al₂O₃). It is even possible, in order to reducethe gas permeation, to produce a barrier layer, applied possibly byextrusion, from a thermoplastic plastics material which is intermixedwith aluminium particles.

To protect the barrier layer against abrasion or detachment, it can beprovided on its radially inner side with a protective layer which isapplied for example by extrusion or by dip coating. Suitable asmaterials for such a protective layer, for gas pipelines and in somecases for high-pressure waste water pipelines, are in particularpolyurethane, especially in its realisation as thermoplasticpolyurethane elastomer (TPU) and polyester, especially in itsrealisation as thermoplastic polyether ester elastomer (TPE), and fordrinking water, service water, long-distance heating and in some caseshigh-pressure waste water pipelines, polyolefins including polyethylene(PE) and copolymers of ethylene and other α-olefins and thermoplasticpolyolefin elastomers (TPO), thermoplastic styrene-butadiene orstyrene-ethylene-propylene copolymers (TPS) and mi inner surface iswrapped.

A further advantageous development of the manufacturing method providesfor a tubing blank, possibly an uncoated woven hose according to priorart, to be drawn over a tubular sheath with low gas permeation andforming a barrier layer, or be pulled into same. If the tubing blank isdrawn over the tubular sheath, formed for example from aluminium foil,the tubing thus produced can be pulled into a pipe. If on the other handthe tubing is to be introduced into the pipe by an inversion method, itis advantageous to pull the tubing blank into the tubular sheath,possibly formed from aluminium foil or some other material with low gaspermeation.

Yet a further advantageous embodiment provides for first of all the pipeto be lined with a tubing blank, having a gas permeation of more than 1ml/(bar d m²) for polar and nonpolar gaseous substances, and thereafterfor the barrier layer to be applied to the inner surface of the tubingblank. By this means, the tubing is only completed during the liningprocess, such that prior assembly of the tubing is not necessary butjust takes place on the building site. The tubing blank must however notexceed a specific gas permeation since possibly for the inversion andgluing to the inner pipe wall under the action of pressure, a minimumimpermeability of the tubing blank is necessary.

In this connection it is particularly advantageous if the barrier layeris sprayed on in a liquid state.

This method makes it possible to adjust the thickness of the barrierlayer in a cost-optimising manner to the respective nominal operatingpressure in the pipe and to a desired service life of the pipe lining.

Further advantageous embodiments are given in the remaining subordinateclaims.

The present invention is now explained with the aid of a number offigures. They show:

FIG. 1a the cross-section of tubing according to the invention in thearrangement according to the invention,

FIG. 1b the cross-section of an arrangement according to the invention,

FIG. 2 pulling a tubular sheath into a pipe using a drawing-in aid,

FIG. 3 a schematic representation of the process of lining by means ofan inversion method.

FIG. 1a shows tubing 1 which comprises a tubing blank 1 a and a barrierlayer lying inside.

The tubing blank 1 a of the tubing 1 is securely connected to thebarrier layer 1 b of the tubing. The tubing blank consists of a textilewoven fabric. It is naturally possible also to provide a textile knittedfabric or some other textile structure, it being advantageous for thematerial of the tubing blank to be able to be saturated with theadhesive. The tubing blank can however also be realised multilayer.

In this case, in addition to a textile structure, an additional layer,possibly with a thermoplastic plastics material extruded on the textilestructure, can be provided. In the fitting position, shown in FIG. 1b,of the tubing, this extruded coating would be arranged in the borderregion between the tubing blank 1 a and the barrier layer 1 b. Amultilayer tubing blank of this type, which contains e.g. a layer formedfrom a thermoplastic polyurethane elastomer, preferably has a gaspermeation<250 ml/(bar d m²). In FIGS. 1a and 1 b the barrier layerconsists of aluminium. The thickness of the aluminium layer is between50 and 200 μm. The barrier layer can however also be a composite of aplurality of layers, e.g. the barrier layer can be formed by analuminium foil coated on one or both sides.

FIG. 1b shows a tubing arrangement or lining formed from tubing 1, whichis connected to the entire surface of the inner wall of a pipe or apipeline 2 by means of an adhesive. The tubing blank 1 a is saturatedwith the adhesive, moreover adhesive is located in the adhesive layer 3.The adhesive layer 3 and the tubing blank 1 a saturated with adhesiveare not completely nonporous; indeed in places there are largishcavities 6 between the pipe inner wall and the inner circumference ofthe tubing blank 1 a. These cavities cause the bursting effect oftraditional tubing, described in the description of prior art in thepresent application, which occurs when an inner pressure P1 in the flowarea 7 of a fluid drops so quickly that pressure compensation from theadhesive layer or the adhesive- saturated tubing blank into the flowarea through the tubing wall is no longer possible. The tubing 1 isparticularly suitable for inner pressures P1≧,

What is claimed is:
 1. A lining for a pipe comprising: a tubing blankand an adhesive for securing the tubing blank to an interior wall of thepipe, including a barrier layer having a permeation of less than 1ml/(bar d m²) for non-polar gaseous substances and a permeation of lessthan 0.1 ml/(bar d m²) for polar gaseous substances.
 2. The lining ofclaim 1 wherein the barrier layer exhibits a permeation of between0.0001 ml/(bar d m²) and 0.01 ml/(bar d m²) for both non-polar and polargaseous substances.
 3. The lining of claim 1 wherein the barrier layerabuts the tubing blank.
 4. The lining of claim 1 wherein the tubingblank comprises a textile structure.
 5. The lining of claim 4 whereinthe textile structure of the tubing blank comprises a woven fabric. 6.The lining of claim 4 wherein the textile structure of the tubing blankcomprises a knitted fabric.
 7. The lining of claim 4 wherein the textilestructure of the tubing blank consists essentially of low diffusionyarns.
 8. The lining of claim 7 wherein the low diffusion yarns consistessentially of a material selected from glass fibers and aramid fibers.9. The lining of claim 4 wherein the adhesive saturates the textilestructure.
 10. The lining of either of claim 1 or 4 wherein the tubingblank further comprises a thermoplastic layer.
 11. The lining of claim10 wherein the thermoplastic layer consists essentially of at least onematerial from the group of polyvinyl alcohols and copolymers thereof,liquid crystal polymers, polyamids, polyacrylonitriles,polyvinylidenechlorides, epoxy resins, and organosilicon compounds. 12.The lining of claim 10 wherein the thermoplastic layer includes aluminumparticles.
 13. The lining of claim 1 wherein the barrier layer consistsessentially of an inorganic material.
 14. The lining of claim 13 whereinthe barrier layer comprises a continuous metal layer.
 15. The lining ofclaim 14 wherein the continuous metal layer consists essentially of atleast one material from the group of aluminum, titanium, copper, zinc,nickel, lead, chromium, iron, iron-zinc alloy and lead-tin alloy. 16.The lining of claim 14 wherein the continuous metal layer has athickness of between 10 μm and 100 μm.
 17. The lining of claim 13wherein the barrier layer consists essentially of a material selectedfrom silicon oxide (SiO_(x) where x≦2) and aluminum oxide (Al₂O₃). 18.The lining of claim 1 further comprising a protective layer on aninterior surface of the barrier layer.
 19. The lining of claim 18wherein the protective layer consists essentially of at least onematerial selected from polyurethane, polyester, polyolefin,styrene-butadien copolymer, styrene-ethylene-propylene copolymer andmixtures of polypropylene and cross-linked ethylene-propylene-dienecopolymers.
 20. The lining of claim 1 wherein the barrier layer isformed at least in part by said adhesive.
 21. A method for lining a pipecomprising the steps of: providing a tubing blank, securing the tubingblank to an interior wall of the pipe with an adhesive, and including abarrier layer having a permeation of less than 1 ml/(bar d m²) fornon-polar gaseous substances and a permeation of less than 0.1 ml/(bar dm²) for polar gaseous substances.
 22. The method of claim 21 wherein theincluding step comprises applying the barrier layer to the tubing blank.23. The method of claim 22 wherein the applying step comprises vacuumdepositing the barrier layer on the tubing blank.
 24. The method ofclaim 21 wherein the including step comprises introducing materialforming the barrier layer into the tubing blank.
 25. The method of claim22 or 23 wherein the including step comprises applying a metal layer bygalvanic means to the tubing blank.
 26. The method of claim 24 furthercomprising the steps of providing a tubular sheath having a sufficientlylow gas permeation to form the barrier layer, and drawing the tubingblank over the tubular sheath.
 27. The method of claim 22 furthercomprising the steps of providing a tubular sheath having a sufficientlylow gas permeation to form the barrier layer, and pulling the tubingblank into the tubular sheath.
 28. The method of claim 22 furthercomprising the steps of providing a metal foil in strip form having asufficiently low gas permeation to form the barrier layer, and wrappingthe metal foil around the tubing blank.
 29. The method of claim 24further comprising the steps of providing a metal foil in strip formhaving a sufficiently low gas permeation to form the barrier layer, andwrapping the metal foil over the inner surface of the tubing blank. 30.The method of claim 21 wherein the including step comprises extrudingthe barrier layer.
 31. The method of claim 21 wherein the including stepcomprises dipping the tubular blank in a material to form the barrierlayer.
 32. The method of claim 21 wherein the including step comprisescoating the tubing blank with a coating with a gas permeation of morethan 1 ml/(bar d m²) for polar and non-polar gaseous substances prior tosaid securing step, and thereafter applying the barrier layer to aninner surface of the tubing blank.
 33. The method of claim 32 whereinthe applying step comprises spraying the barrier layer on in a liquidstate.
 34. The method of claim 32 wherein the applying step comprisesproviding a tubular sheath, placing an adhesive between the tubularsheath an the inner surface of the tubing blank, and pulling the tubularsheath into the tubing blank after the tubing blank is positioned withinthe pipe, and pressurizing the interior of the tubular sheath to securethe sheath to substantially the entire inner surface of the tubingblank.
 35. The method of claim 34 wherein the pulling step comprisesusing a flexible draw-in tube as a drawing-in aid for installation ofthe tubular sheath.
 36. The method of claim 32 wherein the applying stepcomprises providing a tubular sheath having a sufficiently low gaspermeation to form the barrier layer, placing an adhesive between thetubular sheath an the inner surface of the tubing blank, and invertingthe tubular sheath into the tubing blank after the tubing blank ispositioned within the pipe.